Eleocharis palustris (L.) Roem. & Schult.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Rhizomatous perennial; stems scattered or in small clusters, 1–10 dm, slender to very stout; spikelet 5–40 mm, lanceolate to lance-ovate in outline, light to dark brown or chestnut; empty scales (glumes) at the base of the spikelet 1 or 2(3), when solitary commonly ± encircling the stem at base, when 2 or 3 generally extending only ca half-way around, but the lowest one even then sometimes encircling; fertile scales mostly 2–4.5 mm; bristles 4(–8), retrorsely barbed, shortly surpassing the achene, or sometimes reduced or obsolete; anthers 1.3–2.5 mm (dry); style bifid; achene lenticular, yellow to medium-brown, 1–2 mm, very finely cellular-roughened; tubercle 0.4–0.7, constricted at base, narrow and conic to depressed-deltoid; 2n=10–92; a polyploid complex with a degree of morphologic-cytologic-geographic differentiation, but the subgroups apparently inextricably linked, and not yet satisfactorily sorted out into proper infraspecific taxa. Wet places, tolerant of salt and alkali; circumboreal, s. in e. U.S. to Va., Tenn., and Mo. (E. smallii, widespread with us, biglumate, much like European E. palustris proper; E. macrostachya, western, biglumate; E. uniglumis, European, with a single encircling glume; E. halophila, mainly of coastal salt-marshes, much like E. uniglumis, uniglumate, the scales ± tapering to an acute or subobtuse tip; E. erythropoda (E. calva), widespread with us, uniglumate, the scales all broadly rounded or obtuse)